Like others have said, the big question to ask yourself is, do you still love skating and do you look forward to going to the rink most of the time? Or do you have to usually drag yourself to the rink and dread going? If your answer is the latter, it might be time to take a little break for a while, and see if you miss it (or not). It sounds like you might just be getting burned out and need a break--and there's nothing wrong with that! As adults, our reasons for skating are different than young kids, who dream of being famous and going to the Olympics. Most adults skate for personal fulfillment reasons--exercise, stress release, personal achievement, etc.--not to become a famous Olympian one day. So with that in mind, skating is certainly a very expensive thing to do if you don't love it.
As far as your scratch spin goes--my coach has been teaching for 20+ years, and she says that most people are really good at jumping OR spinning, but few truly excel at both (or course, you can work at everything and learn it, but I guess in terms of having more natural ability). You mentioned that you learned your jumps easily, so it might just be that your knack is jumping. I skated for 4 years as a teenager, and never had a great scratch spin. I could do it, but I could never make it go really fast, or hold it for, like, 25 revs. I returned to skating about a year ago after 15 years off at age 32, and it took me 6 months before I could even do any kind of resemblance of a 1-foot spin (like... 3-4 slow revs). It's 5 months later, and I'm still working my butt off on my scratch spin. It's more consistent, but it's still only 6-7 revs and not very fast at all. My coach will say I need to keep my core tighter, or keep my arms tighter to make it go faster, or hold my free leg in front to make it last longer--and of course, I overthink it and the whole spin falls apart. It's frustrating, but I've just accepted the fact that good scratch spins are WAY more difficult than they look, and maybe scratch spins just aren't my "thing." I'm not giving up on it, though. I just accept that spinning is REALLY FREAKING HARD. It's a skill that I'll continue to work on--probably for as long as I continue skating--and it will improve at a snail's pace. We started working on it sit spin last October, and that's in the same boat. But I'm okay with that because I look at the progress I've made on other skills, and also put a lot of focus on improving things I'm good at--making a jump bigger, doing footwork turns with more speed--because that's the kind of stuff that keeps me feeling like I'm making progress--and in turn, makes me feel good about skating. (And for what it's worth, I can't do a back spin at all anymore. I could do it as a teen, but a year later, attempting it just scares the bejeezus out of me!)
So, maybe take a step back from putting so much emphasis on your scratch spin, and look at the things you learned more easily, and can do well (i.e. your jumps). Does that progress make you feel good, and proud? If so, it's probably not time to outright quit skating, but maybe just take a little break, and think about if you'd be happy re-evaluating your goals, so that you're putting less emphasis on the spins that are causing so much frustration, and more emphasis on the things you enjoy doing and excel at. My big thing about skating as an adult is--I'm in it for fun, personal achievement and exercise. Not because I might be able to make a career out of it one day. Therefore, nothing in skating is worth beating myself up over! I just accept that there's stuff I'll learn quickly, and there's stuff that will take forever. There's stuff I'll be good at, and there's stuff that will always feel awkward/unnatural/scary. But that's just the nature of skating. I think the bottom line of skating as an adult is, if you love it, it's totally worth it. But if you really don't love it anymore, it's an awfully expensive thing to keep doing "just because." And if you don't love it anymore, or are just feeling burned out, there's nothing wrong with stepping away, because you can come back at any time.